In Scheme you can define and create new functions and macros at runtime. There is not much else that is dynamic about the Scheme standard[1] because... there's not much else to the Scheme standard.
As for reflection, I see that mainly as a tools/debugging aid, and therefore very implementation-specific stuff. "Dynamic" languages have reflection in their definition because they are mostly defined by implementation.
That said, the Scheme standard doesn't preclude reflectivity at all, nor seems particularly compile-oriented to me. Nowhere it is assumed that implementations be compilers at all.
I think most of the things you find missing there were not left out for efficiency, but because it was rightly considered that they don't belong in the language spec at all.
[1] By the "Scheme standard" I mean R5RS.